Kalanick got good grades and was athletic growing up, running track and playing football. But he was bullied by older students, and later vowed that he'd never be pushed around by anyone again.

Kalanick would eventually follow in the entrepreneurial footsteps of his mom, a retail advertiser: He went door-to-door as a teen, selling knives for Cutco. He then started his first business at 18, an SAT-prep course called New Way Academy.

After being sued by several entertainment companies to the tune of $250 billion, Scour filed for Chapter 11 bankruptcy.

Kalanick rebounded with Red Swoosh, a networking-software company. But he clashed with his new cofounder, Scour cofounder Michael Todd. Between the post-9/11 stock market crash, the company's pushing of legal boundaries by reinvesting its employees' income taxes back into the startup, and a final falling-out between the cofounders, Red Swoosh almost never made it to exit.

But things improved. Kalanick moved back into his parents house and raised more funding. In 2007, Kalanick sold Red Swoosh to Akamai for $23 million and became a millionaire.

Kalanick spent his first year as a millionaire traveling around the world. He went to Spain, Japan, Greece, Iceland, Greenland, Hawaii (twice), France (twice), Australia, Portugal, Cape Verde, and Senegal.

But Kalanick's dislike of taxis stemmed from a bad experience in a cab years earlier: He got into an argument with a taxi driver and jumped out of the moving car.

Garrett Camp, Oscar Salazar, and Conrad Whelan built the first version of Uber, a black-car service called UberCab. Kalanick served as a "mega adviser," though he's previously said his title then was "chief incubator." With UberCab, which cost about 1.5 times as much as a cab, you could request a car in San Francisco by sending a text or pressing a button.

In December 2010, Kalanick became CEO and Graves became Uber's general manager again. According to both, the rearrangement was friendly.

After San Francisco, Uber rapidly expanded its services to other US cities. In May 2011, Uber launched in New York City, now one of Uber's biggest markets: More than 168,000 Uber rides are hailed in New York City every day. Uber now operates in more than 260 North American cities.

Uber is currently valued at $69 billion, making it the most valuable privately-held tech company in the world.

Kalanick — along with Uber cofounder Garrett Camp and Ryan Graves — made Forbes' list of the world's billionaires for the first time in 2015. Cofounders Kalanick and Camp have a larger stake in the company than Graves does, which explains their larger net worths — $6.3 billion each, as opposed to Graves' $1.58 billion.

In early 2015, Uber announced plans to start testing self-driving cars in Pittsburgh. The project has since expanded and Uber now tests its self-driving cars in San Francisco and Arizona. It's a project that Kalanick is particularly passionate about — he believes the future of Uber depends on it.

An Uber self-driving test car in Pittsburgh, Pennsylvania.Uber

"If we are not tied for first, then the person who is in first, or the entity that's in first, then rolls out a ride-sharing network that is far cheaper or far higher-quality than Uber's, then Uber is no longer a thing," Kalanick told Business Insider in August 2016.

Kalanick's personality — described by those who know him as reckless and arrogant, at times — has been the reason Uber has found so much success...

...but it has also backfired for Kalanick and Uber as a whole.

Uber weathered its first scandal in 2014, when in an interview with GQ, Kalanick called the service "boob-er" since it helped attract women.

Fast-forward to February 2017, when a former employee named Susan Fowler alleged in a blog post that she was sexually harassed at Uber and experienced gender bias during her time at the company. Kalanick immediately pledged to look into Fowler's investigations, and hired former US Attorney General Eric Holder to lead the investigation.

But since then, the company has been pummeled by a seemingly never-ending barrage of scandals. The New York Times published a bombshell report in February that alleged employees did cocaine during a company retreat and a manager had to be fired after groping multiple women.

A dashcam video then caught Kalanick losing his cool in an argument with an Uber driver on Super Bowl Sunday after the driver confronted him about lowered fares. Kalanick issued an apology and said he'd seek out leadership help in the form of hiring a COO, a position that has yet to be filled.

Though Kalanick previously would only use Uber to get around and would occasionally drive for Uber himself, he has since hired a private driver.

Kalanick dated violinist Gabi Holzwarth for two years, but the pair called it quits in August 2016. Holzwarth came forward in March 2017 to detail sexism she witnessed at Uber during her time dating Kalanick, including a visit by several Uber executives to an escort-karaoke bar in South Korea.

Uber is also currently embroiled in a legal battle with Google over self-driving car technology. Google claims Uber plotted a "cover up scheme" with former Google employee Anthony Levandowski in order to steal crucial self-driving car technology from Google. In April, Levandowski was fired from Uber.

A self-driving Uber vehicle also jumped a red light in San Francisco. An Uber spokesperson initially said that it was due to "human error," but a report from The New York Times contradicted this, saying it was instead because the tech failed to recognise the red light.

In May, Kalanick was struck by tragedy: His parents, Bonnie and Donald Kalanick, were in a boating accident in California. Bonnie Kalanick died in the accident, and Donald Kalanick was rushed to the hospital in serious condition. Travis Kalanick wrote on Facebook in early June that his father's condition was gradually improving.

In June, Kalanick's right-hand man, chief business officer Emil Michael, resigned from Uber. Michael reportedly believes that his close friendship with Kalanick and a "weak" board of directors led to his ouster.

Also in June, Uber fired more than 20 employees after an investigation revealed 215 claims of harassment at the company. Uber has also released a 13-page report after a four-month investigation into the company's culture by former US attorney general Eric Holder's firm. The report recommends sweeping changes to Uber's hard-partying "bro culture," more executive accountability, and renewed efforts to increase diversity at the company.

Perhaps most damningly, executive Eric Alexander allegedly acquired the medical records of a passenger who was raped by their driver in India, discussed them with Kalanick and Michael, and carried them around for a year. He has now been fired — but when the episode came to light, it led to more calls for Kalanick's resignation. The passenger is now suing Uber.

Earlier in June, Kalanick took a leave of absence from the company to "work on myself" and to deal with his recent family tragedy. The company said that upon his return, he would be stripped of some duties which would be passed on to a new chief operating officer.

But late on Tuesday night, the news broke that the embattled CEO had resigned. "I love Uber more than anything in the world and at this difficult moment in my personal life I have accepted the investors request to step aside so that Uber can go back to building rather than be distracted with another fight," Travis Kalanick said in a statement.

There was reportedly "hours of drama" between Uber's investors, and five demanded Kalanick's immediate resignation. Bill Gurley, who reportedly pushed for the CEO to go, subsequently tweeted: "There will be many pages in the history books devoted to [Travis Kalanick] — very few entrepreneurs have had such a lasting impact on the world."

Bill Gurley.Flickr/TechCrunch

What's next for Travis Kalanick? It's not yet clear. He will remain on the company's board, and still owns a massive stake in the company. "Travis has always put Uber first," the firm's board said in a statement. "This is a bold decision and a sign of his devotion and love for Uber. By stepping away, he's taking the time to heal from his personal tragedy while giving the company room to fully embrace this new chapter in Uber's history."